Field of the Invention
The present invention generally relates to patient interfaces. More particularly, the present invention relates to such interfaces particularly though not solely for use in delivering CPAP therapy to patients suffering from obstructive sleep apnoea (OSA).
Description of the Related Art
In the art of respiration devices, there are a variety of respiratory masks that cover the nose and/or mouth of a human user in order to provide a continuous seal around the nasal and/or oral areas of the face such that gas may be provided at positive pressure within the mask for consumption by the user. The uses for such masks range from high altitude breathing (i.e., aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications.
Such respiratory masks should provide an effective seal against the user's face to reduce the likelihood of leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for the user. This problem is prevalent in those applications, especially medical applications, in which the user wears a mask or patient interface continuously for hours or perhaps even days. In such situations, the user may not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives thus will not be achieved, or will be achieved with great difficulty and considerable user discomfort.
To aid with user comfort, masks can be provided in a range of different sizes. A user will find one particular size in the available range of sizes most suitable for providing an effective seal and a comfortable fit. A single mask frame can be provided to which a range of different sized seals may be fitted. A user chooses the most suitably sized seal from the available range (e.g., the user chooses one size from small, medium, large and extra large) and attaches that seal to the mask frame for use.
A further example of a way in which differently sized users are accommodated is the nasal mask range disclosed in US2010/0006101, the entire contents of which are hereby incorporated by reference herein. As shown in FIG. 1 of this application, three different sized mask bodies 430 and correspondingly sized seal assemblies 440 are provided. A user may select the most suitably sized frame and corresponding seal assembly for use. Various components of the nasal mask disclosed in US2010/0006101 are described below with reference to FIGS. 2 to 6.
The mask assembly 402 comprises a mask body 430 and a mask seal assembly 440. The mask body 430 provides the overall structural support for the mask assembly, and provides a clip type fitting 433 for attaching the mask assembly 402 to headgear 421. The mask body includes a forehead support 431 to which the headgear is also attached.
A rear side of the mask body 430 interfaces to the seal assembly 440. The seal assembly 440 provides a sealing interface against a user's face in use.
The mask body 430 has an inlet for receiving a flow of respiratory gases and exhaust holes 425 to allow exhaled breath to be vented from the mask assembly. The mask body forms an internal cavity to which respiratory gases are supplied via the inlet. The inlet comprises a tubular projection 422 extending from a front side 471 of the mask body 430. A connector 423 connects to the inlet and swivels with respect to the mask body 430, for connecting a supply conduit to the mask body.
The seal assembly 440 comprises a flexible seal 443 attached to a relatively rigid plastic clip 442. The flexible seal 443 is over-moulded to the plastic clip 442 so that the seal assembly 440 forms a single item of the mask assembly 402. The plastic clip has a series of holes 446 around its perimeter. During manufacture, over moulding of the seal to the clip causes the seal material to flow through the series of holes 446. During manufacture, the seal material is cured. Once cured, the seal 443 is mechanically linked to the plastic clip 442 via holes 446, providing a mechanical joint between the clip and the seal. The holes 446 are located through a raised ridge 445 running around the inside perimeter of the clip.
The clip 442 releasably attaches to the mask body in a ‘clip’ or ‘snap’ type engagement. A series of bumps 448, or raised portions, on the mask body 430 interact with corresponding recesses 447 on the clip 442, to hold the clip 442 in place on the body 430. As the clip 442 attaches to the mask body, interference between the clip and each mask body bump 448 causes the clip or the mask body, or both, to deflect to a deflected condition until each bump 448 reaches a corresponding recess 447. Once the clip has been fully engaged with the body, each bump 448 locates within a corresponding recess 447, and the clip or body, or both un-deflect from the deflected condition to an un-deflected or partially deflected condition, the parts being clipped or snapped together in a fully engaged position.
The clip 442 preferably has a relatively long lead in, or ramped profile 449, leading to the clip recess 447. This lead in section extends the full inside perimeter length of the clip 442. The lead-in section assists with the attachment of the clip to the mask body. The clip 442 or mask body 430, or both, are gradually deflected over the length of the lead-in section until the apex of the lead-in section and each mask body bump 448 pass each other. Once the bumps 448 have passed over the lead-in section, the bumps 448 locate within each corresponding recess 447, such that there is little or no interference between the two parts 430 and 442. The two parts un-deflect in a relatively sudden snap action compared to the gradual deflection caused by the lead in section 449 during engagement.
The face seal assembly 440 includes at least one wing portion 444 to assist a user to disengage the face seal assembly from the mask body. The wing portions 444 provide a gripping flange to pull the clip 442 away from the mask body 430.
The nasal mask includes a cushion 441. Cushion 441 is provided around the periphery of the mask, and is surrounded by the seal assembly 440. The cushion 441 provides support to the seal 443 to achieve an effective seal onto the face of the user to reduce the likelihood of leakage.
One end 462 of the mask cushion is shaped to match the shape of the seal in contact with the user's face, and an opposite end 463 is shaped to match the mask body. The cushion includes a raised bridge 465 in the nasal bridge region. The raised bridge 465 can also be described as a cut out section made in the cushion, the cut out being on the mask body end 463 of the cushion. As the raised bridge 465 is unsupported by the mask body 430, it is much more flexible and results in less pressure on the nasal bridge of the patient.
The cushion 441 is located around the outer periphery of the mask body, contacting the mask body except for in the raised bridge portion 465 of the cushion. The cushion is located in a generally triangular cavity 466, the cavity continuing around the periphery of the body, terminating at each side of the nose bridge region 467 of the mask, where the raised bridge portion 465 of the cushion does not contact the mask body 430. The cavity 466 is generally formed by two spaced apart walls 476 and 477. The cushion 441 is a separate item, the seal assembly 440 fitting in place over the cushion to hold it in place within the mask assembly 402.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.